1. Field of the Invention
The present invention relates to construction technology for a path networks which conduct traffic engineering such as route selection and rearrangement of paths. In particular, the present invention relates to a layered network node, a network incorporating the same, a node, and a layered network.
Priority is claimed on Japanese Patent Application No. 2002-293679 filed on Oct. 7, 2002 and Japanese Patent Application No. 2003-036801 filed on Feb. 14, 2003, the contents of which are incorporated herein by reference.
2. Description of Related Art
In the case of networks in which plural layers are intermixed with each other, network management for each layer is often conducted in each layer individually. The network management differs depending on the layer, and there may be mentioned a central-control method in which one apparatus monitors all conditions of the network and controls, and a distributed-control method in which all nodes in the network share information by exchanging the link state. In addition to these, limiting only one layer control, there is a method which divides a network into plural areas, and manages the areas individually.
In the case of conducting distributed-control multi-layer traffic engineering under conditions in which networks of plural layers are intermixed with each other, conventionally, traffic engineering was conducted for the entire network (see, for example, the following documents No. 1 and No. 2). Therefore, there are problems in that a large scale network is enlarged because the information content which is generally treated using routing protocol is represented by OPSF (Open Shortest Path First), etc. Document No. 1
K. Sato, N. Yamanaka, et al., “GMPLS-based photonic multilayer router (Hikari router) architecture: an overview of traffic engineering and signaling technology,” IEEE Commun. Mag., Vol. 40, Issue 3, March 2002 Document No. 2
E. Oki, N. Yamanaka, et al., “A heuristic multi-layer optimum topology design scheme based on traffic measurement for IP+ photonic networks,” Optical Fiber Communication Conference and Exhibit, pp. 17-22, March 2002
This problem will be explained in more detail. FIG. 62 shows a network being comprised by plural network layers. In this example, the network is comprised by an IP layer and a TDM (Time Division Multiplex) layer and a wavelength layer. In this network, each node advertises a link state which is composed from a IP address, a maximum broad band, a band for use, and so on.
A node for setting paths sets paths by conducting calculation based on this link stage whether a TDM path and a Lambda path are to be newly set or not. Also, the node for setting paths sets paths by conducting calculations based on the link stage to find which path will provide minimum cost. In the case of conducting rearrangement of a route of some IP path, at the same time, a calculation is performed to find necessity of rearrangement of a Lambda path in a lower level. In this kind of network, along with enlargement of the network scale, process load such as advertisement volume of link states, calculation amount of route computation, etc., increases. Therefore, scale ability cannot be maintained at some constant scale. The same thing can be said concerning increment of layer to be treated generally.